1. Field of the Invention
The present invention relates to a broadband wireless communication system. More particularly, the present invention relates to an apparatus and a method for performing a plurality of pagings within one paging cycle in a broadband wireless communication system.
2. Description of the Related Art
The Institute of Electrical and Electronics Engineers (IEEE) 802.16m standard which is considered as a next-generation wireless communication system defines an idle mode to reduce power consumption of a terminal. In the idle mode, which is one of operation modes of the terminal, the terminal does not transmit and receive traffic at all. Accordingly, when downlink traffic of the idle terminal takes place, a control signaling for informing of the downlink traffic must precede. The informing of the downlink traffic through the control signaling is referred to as paging. The paging is carried out by a paging group allocated to a corresponding terminal. The paging group is a paging range including a plurality of base stations. When the paging is conducted on a single terminal, the base stations in the paging group allocated to the terminal transmit a paging message.
One terminal can be assigned a plurality of paging groups. When the downlink traffic to the idle terminal takes place or location update should occur, the system pages the terminal using the paging group of a highest rank. When there is no response from the terminal within a certain time interval, the system pages through the paging group of a next rank. As a result, the paging time through the paging group conforms to a paging offset defined individually with respect to each paging group. Paging parameters including the paging group, a paging cycle, and a paging offset are transmitted to the terminal using a DeREGistration-ReSPonse (DREG-RSP) message or a RaNGing-ReSPonse (RNG-RSP) message in case of an idle mode entry or the location update of the terminal.
Meanwhile, the IEEE 802.16m standard is recently provided Machine-to-Machine (M2M) application support. The M2M application supports communication between devices or between a device and a server over a wireless communication network without user's intervention. Adoption of the M2M application allows various scenarios such as smart grid and smart metering. According to the M2M application, the traffic can take place on a time, day, or month basis and good power saving technologies for a communication module are desired. Hence, a longer paging cycle than the predefined paging cycle has been introduced. However, when the paging cycle is increased, the power consumption of the communication module can be reduced. Yet, when the reception of the paging message fails, it may not be possible to receive the paging message until the next paging time. As a result, a paging delay is extended.